Fair Value Measurements - Fair Value Assets and Liabilities Measured on Recurring Basis (Detail) - USD ($) $ in Millions	Sep. 26, 2015	Sep. 27, 2014
Assets:
Assets measured at fair value on a recurring basis	$ 27.7	$ 39.8
Liabilities:
Liabilities measured at fair value on a recurring basis	29.4	35.8
Equity Security [Member]
Assets:
Assets measured at fair value on a recurring basis	15.2	24.4
Mutual Funds [Member]
Assets:
Assets measured at fair value on a recurring basis	5.6	15.4
Interest Rate Cap [Member]
Assets:
Interest Rate Cash Flow Hedge Asset at Fair Value	6.9
Deferred Compensation Liabilities [Member]
Liabilities:
Liabilities measured at fair value on a recurring basis	29.4	35.8
Quoted Prices in Active Market for Identical Assets (Level 1) [Member]
Assets:
Assets measured at fair value on a recurring basis	20.8	39.8
Liabilities:
Liabilities measured at fair value on a recurring basis	29.4	35.8
Quoted Prices in Active Market for Identical Assets (Level 1) [Member] | Equity Security [Member]
Assets:
Assets measured at fair value on a recurring basis	15.2	24.4
Quoted Prices in Active Market for Identical Assets (Level 1) [Member] | Mutual Funds [Member]
Assets:
Assets measured at fair value on a recurring basis	5.6	15.4
Quoted Prices in Active Market for Identical Assets (Level 1) [Member] | Interest Rate Cap [Member]
Assets:
Interest Rate Cash Flow Hedge Asset at Fair Value	0.0
Quoted Prices in Active Market for Identical Assets (Level 1) [Member] | Deferred Compensation Liabilities [Member]
Liabilities:
Liabilities measured at fair value on a recurring basis	29.4	35.8
Significant Other Observable Inputs (Level 2) [Member]
Assets:
Assets measured at fair value on a recurring basis	6.9	0.0
Liabilities:
Liabilities measured at fair value on a recurring basis	0.0	0.0
Significant Other Observable Inputs (Level 2) [Member] | Equity Security [Member]
Assets:
Assets measured at fair value on a recurring basis	0.0	0.0
Significant Other Observable Inputs (Level 2) [Member] | Mutual Funds [Member]
Assets:
Assets measured at fair value on a recurring basis	0.0	0.0
Significant Other Observable Inputs (Level 2) [Member] | Interest Rate Cap [Member]
Assets:
Interest Rate Cash Flow Hedge Asset at Fair Value	6.9
Significant Other Observable Inputs (Level 2) [Member] | Deferred Compensation Liabilities [Member]
Liabilities:
Liabilities measured at fair value on a recurring basis	0.0	0.0
Fair Value, Inputs, Level 3 [Member]
Assets:
Assets measured at fair value on a recurring basis	0.0	0.0
Liabilities:
Liabilities measured at fair value on a recurring basis	0.0	0.0
Fair Value, Inputs, Level 3 [Member] | Equity Security [Member]
Assets:
Assets measured at fair value on a recurring basis	0.0	0.0
Fair Value, Inputs, Level 3 [Member] | Mutual Funds [Member]
Assets:
Assets measured at fair value on a recurring basis	0.0	0.0
Fair Value, Inputs, Level 3 [Member] | Interest Rate Cap [Member]
Assets:
Interest Rate Cash Flow Hedge Asset at Fair Value	0.0
Fair Value, Inputs, Level 3 [Member] | Deferred Compensation Liabilities [Member]
Liabilities:
Liabilities measured at fair value on a recurring basis	$ 0.0	$ 0.0